1. Field of the Invention
The present invention relates to an apparatus and a method for testing a highly integrated semiconductor known as a system on a chip (SOC), and more particularly for testing a SOC comprising a hard disk controller and a read channel.
2. Description of the Related Art
In the last several decades, rapid innovation in hard disk drive technology has occurred in parallel with progress in VLSI technology and software techniques to contribute to miniaturization of hard disk drives and maximization of storage capacity. In accordance with these technology trends, it has become possible to produce a highly integrated circuit known as a system on a chip (SOC). A SOC is a single integrated circuit, i.e., one substrate, that includes functions that previously have been manifested on separate integrated circuits. One type of SOC includes a hard disk controller for a hard disk drive and a read channel for the hard disk drive.
Test circuits for systems fabricated in semiconductor chips as integrated circuits are very well known in the literature and are the subject of many patents. Likewise, hard disk drives, disk controllers, and read channels for hard disk drives are very well known in the literature. For example, see U.S. Pat. Nos. 5,867,033; 5,610,530; 6,075,663; 6,169,413; 5,832,418; and 6,076,180, the contents of each of which are incorporated herein by reference.
Conventionally, the hard disk controller and the read channel have been fabricated in separate semiconductor chips. One problem that has arisen because of this integration on separate chips is that of testing the SOC. A conventional approach to testing the SOC requires the use of an actual hard disk assembly (HDA). This approach has numerous drawbacks. One drawback is the expense associated with using HDA's. A second drawback is the unavailability of the HDA because it is generally being developed simultaneously as the SOC is being developed. A third drawback is the impracticality of testing a SOC with an HDA during the mass production phase. A fourth drawback is that because the HDA is a mechanical hardware device, it is likely to encounter mechanical glitches that make it less reliable for testing purposes. These drawbacks have generated a need for an improved approach to testing a SOC that includes a hard disk controller and a read channel.